The present invention relates to improvement in a CRT (cathode ray tube) anode cap which is provided with an insulated high-voltage supply lead, an anode structure electrically connected with the free end of the insulated high-voltage supply lead for engagement with a CRT anode button and an insulating cap provided at the free end of the high-voltage supply lead for housing the anode.
A CRT anode cap, in general, has an insulated high-voltage supply lead, an anode structure electrically connected with a free end of the insulated high-voltage supply lead for engagement with an anode button and a flexible insulating cap provided at the free end of a high-voltage supply lead for housing the anode structure. The insulated high-voltage supply lead is composed of a core conductor and an outer insulating coating. The insulating coating is removed at the free end of the high-voltage supply lead to expose the core conductor and the anode structure is electrically connected with the exposed portion of the core conductor. In addition, the insulating cap is provided at the free end of the high-voltage supply lead for housing the anode structure.
The anode structure has a square-shaped conductive plate member, square-shaped conductive plate members which are extend from left and right free ends portions of the conductive plate member and are folded back to the right and the left, respectively to underlie the front half-portion of the conductive plate member in opposing relation thereto, square-shaped conductive plate members which are extend downward from the rear free end portions of the conductive plate members, respectively, and conductive plate members which are extend outwardly from the front and rear end portions of the conductive plate member, respectively.
In this case, the free end portion of either of the conductive plate members extends in a manner to make sliding contact with the upper surface of the other conductive plate member, and at least the right-hand portion of either of the conductive plate members makes sliding contact with or lies adjacent to at least the left-hand portion of the other conductive plate member on the front side thereof. The conductive plate member has, in its lower left portion, an anode button engaging piece provided with a stepped portion extending outwardly to the left and a slope extending down therefrom to the right, and a flange receiving facet extending upward from the stepped portion; furthermore, the conductive plate member has a holding piece formed by bending, for example, to the front, the marginal portion extending upward from the flange receiving facet.
In this case, the opposite surfaces of the anode button engaging piece extending from the opposite surfaces of the conductive plate member, respectively, to face the front and the rear, and the stepped portion and the slope of the anode button engaging piece form a part of the periphery of the anode button engaging piece and the flange receiving facet forms a left part of the periphery of the conductive plate member.
The conductive plate member has, in its lower right portion, an anode button engaging piece provided with a stepped portion extending outwardly to the right and a slope extending down therefrom to the left, and a flange receiving facet extending upward from the stepped portion; furthermore, the conductive plate member has a holding piece formed by bending to the front the marginal portion extending upward from the flange receiving facet.
In this case, the opposite surfaces of the anode button engaging piece extending from the opposite surfaces of the conductive plate member, respectively, to face the front and the rear, and the stepped portion and the slope of the anode button engaging piece form a part of the periphery of the anode button engaging piece and the flange receiving facet forms a left part of the periphery of the conductive plate member.
The conductive plate member is formed by turning back the front free end portion of the conductive plate member at the center thereof to overlie it in opposing relation thereto and has core conductor holding pieces respectively bent down from the left-hand and right-hand free end portions of the backwardly extending portion. The conductive plate member has high-voltage supply lead holding pieces respectively bent up from its left-hand and right-hand free end portions. The anode structure of the above-mentioned construction can be obtained by punching and bending a conductive and resilient plate such as stainless steel.
The conductive plate members of the anode structure constitute an engaging portion for engagement with the CRT anode button. The conductive plate members form a radioactive-rays shielding portion for shielding radioactive rays emanating from the anode button. The conductive plate member is electrically coupled with the high-voltage supply lead, holding the exposed end portion of its core conductor by the core conductor holding pieces with a resilient force. The conductive plate member holds the high-voltage supply lead at one insulated end portion by the core conductor holding pieces with a resilient force.
The CRT anode button comprises a conductive cylindrical member, a conductive plate member extending therefrom to close the bottom opening of the cylindrical member, and a ring plate flange extending from the upper end of the cylindrical member inwardly thereof to define an opening for the cylindrical member. The CRT anode button is buried in a CRT envelope wall, with the plate member coupled with a conductive layer formed on the interior surface of the envelope wall and the cylindrical member communicating with the outside through the opening defined by the flange.
With the above-mentioned CRT anode cap, the conductive plate member of the anode structure when the latter is not engaged with the CRT anode button is biased to the left through the conductive plate member by the resiliency of the bend between the conductive plate members, and the conductive plate member is biased to the right through the conductive plate member by the resiliency of the bend between the conductive plate members.
By pressing the anode structure against the CRT anode button from the side of the insulating cap, the slope of the engaging piece of the conductive plate member and the slope of the engaging piece of the conductive plate member are urged against the open portion of the flange of the anode button to slide down into the cylindrical portion of the anode button. Namely, by the downward sliding movement, the lower left portion of the conductive plate member and the lower right portion of the conductive plate member are pressed to the right and left, respectively, against the aforementioned resiliency and the lower end portions of the both conductive plate members are inserted into the cylindrical portion of the anode button. Upon disengagement of the slopes from the open portion of the flange of the anode button, the conductive plate members are snapped back by the aforementioned resiliency to urge their flange receiving facets against the inside of the opening of the flange.
After this, the anode structure is released and fitted into the anode button. Once the anode structure is thus attached to the anode button, the anode structure is firmly held in the anode button in such a manner that their flange receiving facets are resiliently urged against the open portion wall of the flange of the anode button and their stepped portions of the engaging pieces of the conductive plate members abut against the undersurface of the flange.
The anode structure can easily be detached from the anode button by raising the former from the latter while pressing inwardly the holding pieces of the conductive plate members through the insulating cap against the aforementioned resiliency to disengage the flange receiving facets of the engaging pieces.
The CRT anode cap described above allows much ease in attaching the anode structure to the anode button as it is sufficient only to press the former toward the latter as described above and in detaching the anode structure from the anode button as it is sufficient only to bring up the former while holding it as described above. With the anode structure held on the anode button, the conductive plate members entirely cover the anode button to effectively prevent leakage of radioactive rays therefrom to the outside.
Moreover, when the anode structure is held on the anode button, the flange receiving facets of the conductive plate members are urged with a large point- or line-contact pressing force at a negligibly small contact resistance against the open portion of the flange of the anode button by virtue of the resiliency of the bends between the conductive plate members and between the conductive plate members, ensuring to achieve reliable electrical connection between the anode structure and the anode button.
The CRT anode structure of the above-mentioned prior art, wherein the insulated high-voltage supply lead must be held at its core conductor by the conductive plate member and at its insulated end portion by the conductive plate member to connect the high-voltage supply lead with the anode structure, requires making the conductive plate members firmly grasp corresponding portions of the high-voltage supply lead by using a pressing tool, for example, pliers. This assembling work is considerably hard. The high-voltage supply lead, if insufficiently held by the plate members, may easily slip out from the anode structure if the lead is forcibly pulled in the event of engaging of the anode structure with any obstruction.